GASOLINE ENGINE 8.1 S INBOARD MODELS
Page 21 of 58
Propeller Selection
IMPORTANT: Installed propeller must allow engine to run at its specified maximum
WOT rpm. Use an accurate service tachometer to verify engine operating rpm.
It is the responsibility of the boat manufacturer and/or the selling dealer to equip the power
package with the correct propeller. Refer to Quicksilver publication - Everything You Need
To Know About Propellers P/N 90-8614492. Specified engine WOT and operating rpm
range are listed in the Mercury MerCruiser Operation, Maintenance and Warranty Manual
attached to the engine.
Select a propeller that will allow the engine power package to operate at or near the top end
of the recommended WOT operating rpm range with a normal load.
If full throttle operation is below the recommended range, the propeller must be changed
to prevent loss of performance and possible engine damage. On the other hand, operating
an engine above the recommended operating rpm range will cause higher than normal wear
and/or damage.
After initial propeller selection, the following common problems may require that the
propeller be changed to a lower pitch.
•
Warmer weather and greater humidity cause a loss of rpm.
•
Operating in a higher elevation causes a loss of rpm.
•
Operating with increased load (additional passengers, pulling skiers) causes a loss of
rpm.
For better acceleration, such as is needed for water skiing, use the next lower pitch
propeller. Do not operate at full throttle when using the lower pitch propeller but not pulling
skiers.
Because of the many variables of boat design, only testing will determine the best propeller
for a particular application. Available propellers are listed in the Quicksilver Accessories
Guide.
See BOAT IN THE WATER TESTS, Maximum RPM Test at the back of this manual.
RPM REV-LIMITER
IMPORTANT: When selecting a propeller consider this additional information, if
applicable:
The engines listed in the following chart are equipped with an rpm rev-limiter that is
set to an upper (or limited) rpm amount. This limit is slightly above the normal
operating range of the engine and is designed to help prevent damage from
excessive engine rpm. Once the rpm drop into the recommended operating rpm
range normal engine operation resumes.
Engine Rev-Limiter
Model
Engine Recommended
Operating RPM Range
Rev-Limit RPM Setting
8.1 S HO
4400 - 4800
4950
8.1 S Horizon
4200 - 4600
4750
